Synthesis of Some New Thiourea Derivatives and Their Influence on Biological and Genetic Effects of Gamma Rays*

The synthesis of the new radioprotective compounds ATB (I, 2-allylthioureidobenzoic acid), PTB (II, 2-phenylthioureidobenzoic acid), A-2-PTU (III, N-allyl-N"-2-pyridylthiourea), and P-2-PTU (IV, N-phenyl-N"-2-pyridylthiourea) and their influence on biological and genetic effects of gamma rays was studied. In result of investigations it must be noted that PTB displayed radioprotective effect as a result of which more plants in M₁ germination and survive in M₂ of the induced mutations is increased. The cytological analysis reveals that the studied substance (PTB) decreases chromosome aberration in meristem cells of pea roots almost twice as a result of postirradiation treatment. The effect of A-2-PTU in the experiments with peas greatly depends on the dose of irradiation, i.e., on the degree of damaging of the processes of cell restoration and the possibility of their partial restoration after the treatment with the protector. The results obtained suggest that chemical compounds of N,N"-disubstituted thiourea group (A-2-PTU and P-2-PTU) exert strong radioprotective effect in the experiments with peas. This is of great importance to modern radiobiology and radiation mutagenesis and also to protect hereditary structures against radiation.     

Radioprotective effect of novel disubstituted thioureas on pea (Pisum sativum L.) development

The review presents our research on the influence of novel thiourea compounds on the biological and genetic effect of gamma-rays using in vivo and in vitro systems of pea. Some novel disubstituted thioureas: o-allylthioureidobenzoic acid (ATB); o-phenylthioureidobenzoic acid (PTB); N-allyl-N'-2-pyridylthiourea (A-2-PTU); N-phenyl-N'-2-pyridylthiourea (P-2-PTU) and 1,4-allylthioureidosalicylic acid (ATUS) were examined. Pea (Pisum sativum L.) seeds from five varieties were used. Experiments in vivo and in vitro were carried under laboratory, greenhouse and field conditions. The data revealed the PTB radioprotective effect demonstrated by: reduction of chromosome aberrations by 2 folds; 50% increase of germinating and surviving plants in M1; twice higher frequency of induced mutations in M2 generation relative to irradiation without PTB treatment; decreasing the level of induced radiation suppression leading to favorable effect on the initial stem and root development of pea. ATB radioprotective effect was demonstrated in vitro by: 25-35% stimulation of organogenesis; by 20-50% increase in bud formation; by 25% stimulation of growth. The effect of A-2-PTU and P-2-PTU depended on the irradiation dose. The protective effect of A-2-PTU is more pronounced at lower irradiation dose, while the effect of P-2-PTU is more pronounced at higher irradiation dose. ATUS, opposite to the other compounds, revealed radiosensibilizing effect by: 16-27% increase in lethality caused by gamma-rays leading to lower number of germinating and surviving plants in M1; 50% decrease in the number of induced mutations in M2 generation; limiting the types of induced mutations at the higher irradiation dose. As a result of the experiments useful mutation forms were obtained, characterized with: earliness, lodging and disease resistance; higher productivity.     

Short-term effects of thyroid hormones on lipogenic enzymes and 14C-acetate incorporation into various lipid classes: in vivo and in vitro studies

Short-term effect of 3,5,3'-triiodothyronine (T3) and 3,5-diiodothyronine (T2) on lipid metabolism in the liver of Anabas testudineus was examined. In vivo injections of both T3 and T2 at a concentration of 10 ng/g body weight increased malic enzyme (ME), glucose-6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6PGDH) activity compared to 6-propylthiouracil (6-PTU) treated group. Treatment of 6-PTU results in the accumulation 14C-acetate into fat and thyroid hormones' treatment reduce it. In vitro experiments show that malic enzyme activity is augmented only by high concentration of T3 (10(-7) M) where as all concentrations of T2 increase its activity. In vitro studies with T3 showed a biphasic effect on cholesterol content. Conversely T2 in vitro, reduced cholesterol content with all concentrations. From these results it can be concluded that both T3 and T2 have short-term effect on lipid metabolism in Anabas.     

Radioprotective action of catecholamines on a Chinese hamster fibroblast culture

The radioprotective ability of adrenaline, noradrenaline and isoproterenol in various concentrations has been studied in experiments on cultured Chinese hamster fibroblasts in vitro. Radioprotective effect of isoproterenol is pronounced at 10(-8)M concentration; adrenaline and especially noradrenaline are effective at higher concentrations. The antagonist of beta-adrenergic receptors propranolol blocks the radioprotective effect of catecholamines on cells. The beta-adrenergic mechanism of catecholamines radioprotective action on the mammals cells is under discussion.     

Possible role of GH/IGF-1 in the ovarian function of adult hypthyroid rats

We have monitored estrous cycle and measured serum estradiol, GH, IGF-1, T4 and T3 levels in adult hypothyroid female rats which were divided into four groups: H group, hypothyroid rats without treatment; H-T4 group, hypothyroid rats injected daily with T4; HT4-PTU group, hypothyroid rats injected daily with T4 plus PTU (propylthiouracil), and H-T4-IOP group, hypothyroid rats injected daily with T4 plus IOP (iopanoic acid); Euthyroid rats (E group) were used as control. Our results indicate that the lack of sexual cycle in H animals was associated with lower values of estradiol, GH and IGF-1 in comparison to E group; the restoration of sexual cycle in H-T4 group was associated with values of estradiol, GH and IGF-1 higher than those of H group, whereas in H-T4-PTU and H-T4IOP groups the restoration was associated with higher values of GH and IGF-1 and values of estradiol similar to those of H group. These data could suggest a potential role of GH/IGF-1 axis, at least in part, in the lack of sexual cycle in H group and in the ovulation induction in H-T4, H-T4-PTU and H-T4-IOP groups.     

Isoflavone genistein-8-c-glycoside prevents the oxidative damages in structure and function of rat liver microsomal membranes

Bioflavonoids (polyhydroxyphenols) are ubiquitous components of plants, fruits and vegetables; these compounds are efficient scavengers of free oxygen radicals and peroxides. The aim of this study was to investigate the antioxidant and radioprotective effects of genistein-8-C-glicoside (G8CG), an isoflavone, isolated from the flowers of Lipinus luteusl L. G8CG prevents dose-dependently the destruction of the cytochrome P-450 and its conversion to an inactive form cytochrome P-420, inhibits membrane lipid peroxidation and membrane SH-group oxidation in isolated rat liver microsomal membranes under tert-butylhydroperoxide-induced oxidative stress. Single whole-body gamma-irradiation (1 Gy) of rats results in blood plasma and liver microsomal membrane lipid peroxidation, impairments of microsomal membrane structure and function. Rat treatment with G8CG (75 mg/kg) developed the clear protective effect, stabilized membrane structure and improved the parameters of the monooxygenase function. We can conclude that G8CG can be used as antioxidant and radioprotective agent.     

Two proteins with gamma-carboxyglutamic acid in frog bone: isolation and comparative characterization

Two gamma-carboxyglutamic acid-containing proteins were purified from neutral (pH 7.5) EDTA-extract of frog, Rana catesbiana, cortical bone by Sephadex G-75 gel filtration, DEAE-Sephadex A-25 chromatography and successive hydroxyapatite column chromatography. These two bone gamma-carboxyglutamic acid-containing proteins, termed osteocalcin, P-1 and P-2, had molecular weights of about 5100 and 4900, respectively, based on their amino-acid composition. Both species of osteocalcin have two gamma-carboxyglutamic acid residues, one disulfide bond, but there was no 4-hydroxyproline in either molecule. Each N-terminus of both proteins was acetylated and each C-terminal amino acid was lysine. The isoelectric points of P-1 and P-2 are 4.02 and 3.91, respectively, and their pI values shifted to more neutral pH in the presence of calcium ions. Equilibrium dialysis has indicated that each of these two proteins binds specifically 2 mol Ca2+, and nonspecifically more, 4-5 mol, Ca2+ in 0.02 M Tris-HCl/0.15 M NaCl (pH 7.4), at 4 degrees C. By the best-fitted calculation, P-1 had one high affinity Ca2+-binding site (Kd1 = 0.17 mM) and one lower affinity site (Kd2 = 0.29 mM), and P-2 contained one high affinity site (Kd1 = 0.154 mM) and one lower affinity site (Kd2 = 0.67 mM).     

Amino acids and their derivatives as radioprotective agents

Summary Numerous amino acids and their analogs are capable of protecting biological systems from the toxic effects of ionizing radiation. These radioprotective agents can be classified into two broad groups, depending upon the presence or absence of a free or potentially free sulfhydryl group. The sulfhydryl-containing compounds have been studied extensively and are thought to exert their radioprotective effects by several mechanisms, including free radical scavenging and hydrogen atom donation. Several non-sulfhydryl-containing amino acids are also being investigated for their radioprotective effects. These agents are less well known than the familiar sulfhydryl compounds, but possess very interesting protective qualities. In short, the study of amino acids and their derivatives as radioprotective agents continues to contribute to an understanding of processes involved in radiation toxicity and to offer new compounds with potential application to situations of human exposure.     

Radioprotective properties of indralin combined with cystamine and mexamine

The study of indralin radioprotective properties at its joint application with cystamine and mexamine was carried out in the experiments on inbred mice and rats. The mice and rats were exposed to whole-body y-irradiation at a dose of 9.0 and 9.5 Gy, correspondingly. A combined parenteral administration ofindralin and cystamine at a dose of 25 mg/kg showed ponentiaton of indralin radioprotective properties up to a level of the ED50 effect versus the absence of or a weak radioprotective effect in the case of their separate application. In the experiments on rats, indralin (50 mg/kg) and mexamine (12 mg/kg) injected intraperitoneally almost completely eliminated the animal mortality from the intestinal syndrome of acute radiation sickness amounting in the control radiation group to 60% on the 7th day after exposure to radiation at a dose of 9.5 Gy. However, at the above conditions, radioprotectors at these doses had a low-level radioprotective action at the onset of the bone marrow syndrome of acute radiation sickness. Combined application of indralin and mexamine at the same doses and at the same conditions led to a radiation protection 50% as high as in the case when radioprotectors were applied separately at a double dose.     

Synthesis and biological evaluation of new spin-labeled derivatives of podophyllotoxin

In order to find compounds with superior bioactivity and less toxicity, a series of spin-labeled podophyllotoxin derivatives were synthesized and tested for the partition coefficients and cytotoxicity against P-388 and A-549. Furthermore, we also determined antioxidant activities of target molecular in tissues of SD rats by the TBA method. Results revealed that most synthesized compounds showed more significant cytotoxicity against P-388 and A-549 in vitro than VP-16. Among them, 9d exhibited most potent cytotoxicity against P-388 and A-549 cells (IC50 is <0.01 and 0.13 microM, respectively). Also, the antioxidative activities showed that the modified compounds of 4'-demethylepipodophyllotoxin (9a-d and 10a-c) are higher than those of podophyllotoxin series (8a-d). The relationship between the cytotoxicity and antioxidative activity discussed.     

Analysis of MIF,FCGR2A and FCGR3A gene polymorphisms with susceptibility to pulmonary tuberculosis in Moroccan population

In order to investigate the influence of functional polymorphisms of macrophage migration inhibitory factor(MIF),Fcg receptors CD16A(FCGR3A) and CD32A (FCGR2A) genes on susceptibility to pulmonary tuberculosis(PTB)in the Moroccan population,we analyzed 123 patients with PTB and 154 healthy controls.The genotyping for MIF-173(G/C)(rs755622),FCGR2A-131H/R(rsl801274)and FCGR3A-158V/F(rs396991) was carried out using TaqMan SNP Genotyping Assay method.We found a statistically significant increase of the MIF-173CC homozygote genotype and MIF-173*C allele frequencies in PTB patients compared with healthy controls (17.07%versus 5.84%,P=0.003;and 35.37%versus 26.30%,P=0.02;respectively).In contrast,no association was observed between CGR2A-131H/R and FCGR3A-158V/F polymorphisms and tuberculosis disease.Our finding suggests that MIF-173*C variant may play an important role in the development of active tuberculosis.     

Synthesis and antitumor activity of s-tetrazine derivatives

Fifty-five compounds of s-tetrazine derivative including hexahydro-, 1,6-dihydro, 1,4-dihydro-, 1,2-dihydro- and aromatic s-tetrazine were prepared. Their antitumor activities were evaluated in vitro by MTT method for P-388 cell and SRB method for A-549 cell. The results show that there are 9 compounds which in 10(-6) microM have more than 50% inhibition rate to A-549 cancer cell growth, and 7 compounds in 10(-6) microM have more than 50% inhibition rate to P-388 cancer cell growth. The IC(50) of compound 3q for P-388, Bel-7402, MCF-7 and A-549 are 0.6 microM, 0.6 microM, 0.5 microM and 0.7 microM, respectively. So s-tetrazine derivative is a kind of compound which possesses potential antitumor activities and is worth to research further.     

Effect of agents for the chemical prevention of radiation sickness on the cyclic nucleotide content in the bone marrow of mice

The effect of different chemical compounds on the cAMP/cGMP ratio in the bone marrow of mice and radioresistance of animals has been studied. It has been shown that all compounds possessing radioprotective properties give rise to the cAMP/cGMP ratio in the bone marrow of mice. No changes in cAMP and cGMP level were noted after the administration of nonradioprotective substances. The maximal radioprotective effect coincide in time with the largest increase of the cAMP/cGMP ratio. The injection of radioprotectors at different doses demonstrate clearly that only at radioprotective doses the increase in the cAMP/cGMP ratio takes place. The administration of some substances 2, 15 and 60 min after the irradiation of mice shows that the radioprotective effect, though modest, was evident only in one case of elevated cAMP/cGMP ratio (the injection of 2-Mercaptoethylamine 2 min after the irradiation). Evident radioprotective effect occurs at the cAMP/cGMP ratio of about 170-200%; the ratio of about 130-140% corresponds to small radioprotection.     

Dna Radiation Damage and its Modification by Metallothionein

Thiol compounds have long been known to protect living cells against the harmful effects of ionizing radiation. Maetallothionein is a naturally occurring low molecular weight polypeptide rich in cysteine residues and may be useful in protection against low-level radiation effects.

Radiation damage to DNA and its nucleotide components and the radioprotective effect of metallothionein have been studied in model chemical systems and compared to its effect on cells. Metallothionein acts both as a free radical scavenger and a reductant, and its radioprotective effectiveness has been studied as a function of dose, drug concentration, and in the presence and absence of oxygen. It is more effective in protecting against sugar-phosphate damage under hypoxic conditions. The chemical modification is greater than that of cell killing as measured by the loss of colony-forming ability. Dose reduction factors greater than two are observed for DNA radioprotection, but the values in cells are much lower. These findings will be discussed in terms of the molecular mechanisms and their implications.     

Dna Radiation Damage and its Modification by Metallothionein

Thiol compounds have long been known to protect living cells against the harmful effects of ionizing radiation. Maetallothionein is a naturally occurring low molecular weight polypeptide rich in cysteine residues and may be useful in protection against low-level radiation effects.

Radiation damage to DNA and its nucleotide components and the radioprotective effect of metallothionein have been studied in model chemical systems and compared to its effect on cells. Metallothionein acts both as a free radical scavenger and a reductant, and its radioprotective effectiveness has been studied as a function of dose, drug concentration, and in the presence and absence of oxygen. It is more effective in protecting against sugar-phosphate damage under hypoxic conditions. The chemical modification is greater than that of cell killing as measured by the loss of colony-forming ability. Dose reduction factors greater than two are observed for DNA radioprotection, but the values in cells are much lower. These findings will be discussed in terms of the molecular mechanisms and their implications.     

Triiodothyronine and melatonin influence antioxidant defense mechanism in a teleost Anabas testudineus (Bloch): in vitro study

The effect of the hormones triiodothyronine (T3) and melatonin on antioxidant defense system was studied in 6-propyl thiouracil (6-PTU)-treated or photoperiod-exposed teleost Anabas testudineus. 6-PTU (2 microg/g) treatment or photoperiod exposure (24 h) increased malondialdehyde (MDA) and conjugated dienes (CD) concentrations, indicating increased lipid peroxidation (LPO) in the experimental conditions. T3 or melatonin (10(-6) M) treatment for 15 min in vitro in PTU-treated fish reversed the activity of superoxide dismutase (SOD), catalase and glutathione content. T3-treated group showed no change in glutathione peroxidase (GPx) activity, whereas melatonin treatment decreased its activity. T3 inhibited glutathione reductase (GR) activity. Photoperiod exposure (physiological pinealotomy) induced a stressful situation in this teleost, as evidenced by LPO products and antioxidant enzyme activities. Melatonin and T3 treatment for 15 min in vitro also reversed the effect of photoperiod on peroxidation products and the SOD and catalase activities. GR activity decreased in photoperiod-exposed group and melatonin and T3 treatment reversed the activities. The antioxidant enzymes responded to the stress situation after 6-PTU treatment and photoperiod exposure by altering their activities. The study suggested an independent effect of T3 and melatonin on antioxidant defence mechanism in different physiological situations in fish.     

General characteristics and comparative evaluation of the radioprotective properties of aryl alkyl amine adrenomimetics in experiments on mice]

The radioprotective effect (RPE) of some arylalkylamines (AAAs) was studied in experiments on mice. Mesaton and its close analogues were injected subcutaneously 15 minutes prior to irradiation at a dose of 800 rad. The protective effect is exerted by AAAs in low doses (25--50 mumole/kg), the compounds show stable and high RPE (80--80% survival, dose reduction factor being 1.3--1.4) and low toxicity (LD50 = 4--8 mumole/kg). AAAs studied are not less effective than aminothiols. Their pharmacological spectrum--K = LD50/ED50 (200--500) is superior to that of known aminothiols and indolylalkylamines.     

Radioprotective properties of indralin combined with cystamine and mexamine

The radioprotective properties of indralin when it is used in combination with cystamine and mexamine are studied in inbred mice and rats. The mice and rats are irradiated with γ rays emitted by ⁶⁰Co at doses of 9.0 and 9.5 Gy, respectively. A combined parenteral administration of indralin and cystamine in mice at doses of 25 mg/kg each is revealed to potentiate the radioprotective properties of indralin up to a level close to the ED₅₀ effect, while the separate application of these drugs in doses of 25 mg/kg each has no or a very weak radioprotective effect. Indralin (50 mg/kg) and mexamine (12 mg/kg) injected intraperitoneally in rats are found to almost completely eliminate the animal mortality caused by gastrointestinal acute radiation syndrome; the mortality in the control radiation group reaches 60% on the seventh day after the animals have been exposed to radiation at a dose of 9.5 Gy. However, if bone-marrow acute radiation syndrome develops under the above condition of super-lethal dose, the radioprotectors have a low radioprotective effect. Under the this condition, the combined application of indralin and mexamine in the same doses has 50% of radioprotective effect reached by applying these radioprotectors separately in double doses.     

Radiation-modifying effect of quinoline derivatives

In experiments with hybrid mice (CBA X C57Bl)F1 and tetrahybrids (CBWA) a study was made of the radio-modifying properties of twelve quinoline derivatives. Among them three preparations, including quipazine [1(2-quinolyl)piperazine], possessed a 50% radioprotective effect. The radioprotective effect of piperazinylcinchonine acid hydrazides was the same as that of mexamine.     

Radioprotective effectiveness and toxicity of 4,5-disubstituted tryptamines

In experiments on mice a study was made of different substituents in the 4th position of the indole ring of 5-methoxytryptamines (5-MOT) on toxicity and radioprotective efficiency of the compounds of this class. It was shown that the administration of the amino-group to a mexamine molecule increased the preparation toxicity; the nitro-group somewhat diminished the toxic properties, and the acetylamino group did not change 5-MOT toxicity. A 5-MOT derivative with a nitro group possessed the strongest radioprotective action. The radioprotective efficiency of these compounds persisted for 1-2 h.